 Vigesimal numeral systems

The vigesimal numeral system is a base-20 counting system. Unlike the more familiar decimal system, which is base-10, or the hexadecimal system, which is base-16, the vigesimal system uses twenty unique symbols to represent values. This means that after counting to 19, the next number would be represented as 20 (analogous to how in decimal after 9 comes 10).